Finding the Fourth Proportional to 1,007.94, 1,390.86 and 565.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.94 : 1,390.86 = 565.80 : x
2. Step 2: Convert to fraction form
   1,007.94/1,390.86 = 565.80/x
3. Step 3: Cross multiply
   1,007.94x = 1,390.86 × 565.80
4. Step 4: Simplify right side
   1,007.94x = 786,948.59
5. Step 5: Solve for x
   x = 786,948.59/1,007.94
6. Step 6: Final answer
   x = 780.75